Method of preparing microporous sheet structures

ABSTRACT

SHAPED PRODUCTS ARE OBTAINED BY COAGULATING AQUEOUS DISPERSIONS (LATICES) OR POLYMERS OF OLEFINICALLY UNSATURATED COMPOUNDS, FOR EXAMPLE AN EMULSION OF POLYVINYL CHLORIDE, BY PREPARING A POLYURETHANE-POLYUREA IN THESE DISPERSIONS.

Patented Feb. 29, 1972 3 646 178 which contain the coagulated dispersions in a finely divided form such as, for example, fiber fleeces. Sheet struc- METHOD gggmgggg tures such as coatings and foils which in turn can be Harm Tmiibel, Leverkusen, Bruno Zorn Cologne F]mard, applied to substrates by bonding with adhesives, for examand Klaus Kiinig and Wolfgang Heydkamp, Leverkusen, 5 P are Preferred- Germally, assigllol's t0 Fafbellfabl'ikell Bayer Akfiell- The aqueous dispersions of polymers of unsaturated gesellschaft, Leverkusen, Germany compounds employed in this invention include latices of l Filed M 1969 thermoplastic or clastomeric polymers obtained from Clams pnomy p g gg g g polymerizable monoor diolefinically unsaturated com- Int CL 329d 27/04,. 6 41/04 10 pounds or copolymers thereof. Any such ordinary com- U.S. Cl. 264-41 4 C i mercial dispersions of this type may be used such as,

for example, rubber latices of many different types including natural rubber latices, polybutadiene latices, URE styrene-butadiene rubber latices, polyisoprene latices, ni- ABSTRACT OF DISCLOS trile rubber latices (butadiene-acrylonitrile and butadiene- PF produfits are obtamed by coagulalfmg aqueous acrylonitrile-methacrylic acid copolymers), latices of dlsperslons Games) of Polymers of thermoplastic resins such as polyvinyl chloride, styrene, urated compounds, for example an emulslon 0f po y acrylonitrile or polystyrene and so on. The latices usually b e by PmParmg a polyurethane"polyurea these contain from about 5% to about 70% solids and those dlspel'slonscommercial latices having a solids content of between about and about 60% are generally preferred. La The production of shaped products, especially of sheet tices which are particularly suitable, together with their structures such as coatings and foils, from aqueous polyproperties, are listed in the following Table C.

TABLE C.COMMERCIAL POLYMER DISPERSIONS Physical properties of the polymer Percent in Particle No. Polymer water Defo hardness size (m.)

01--.. (34%) copolymer of acrylonitrile butadiene and methacrylic acid 60 80 02-". Butadiene-acrylonitrile and 4% methacrylic acid 60 30 C 3 Butadiene-acrylonitrile-styrene and 15% methacrylic acld 60-80 4.-.. 2-chlorobutadiene polymerized with a compound containing carboxyl groups 2-chlorobutadiene Butadiene-(28%)acrylonitrile Polyisobutylene Polyvinyl chloride 9-. Acrylate 10-- Vinylidene chloride 11. 33% acrylonitrile, 67% butadlene OOOOOOOQ eet" 1 Copolyrner of acrylic acid, butyl acrylate and styrene.

mer dispersions is known. Such shaped products can also The monomers used in the preparation of such latices be obtained from polyurethane dispersions containing are known and described, for example, in Houben-Weyl emulsifiers. Notwithstanding, the preparation and use of Makromolekulare Stofife, part 1, Stuttgart 1961, pages a mixture of these two types of dispersions is very difii 26 to 30 and pages 32 to 33 as well as in the literature cult because of their incompatibility and products ob- 45. cited therein.

tained from such mixtures have unsatisfactory properties. Examples of suitable polymers, all of which are com- It is therefore an object of this invention to provide mercially available, are: Natural and synthetic rubbers shaped products and a method for the production thereof such as polybutadienes, polyisoprene, polychloroprene, which is devoid of the foregoing disadvantagesstyrene-butadiene rubber, butadiene-acrylonitrile copoly- Another object of this invention is to provide micromers, and more or less thermoplastic materials such as porous sheets from aqueous dispersions of polymers which polyvinyl chloride, polyvinylidene chloride, polystyrene,

microporous sheets have good physical and mechanical ethylene-vlnylacetate p y p y ryl nitrile, styproperties, rene-acrylonitrile copolymers and more specialized prod- A further object of this invention is to provide a methucts suchfils PP Y of butadiene, 'Y f od for the preparation of shaped products wherein a mixmPthacl'yhc acld, p ly rs of butadiene, acryloniture of two types of dispersions which were formerly intrue, Styrene and methacryhc acld' compatible is gmployei The polyurethane polyureas produced in these latices The foregoing objects and others are accomplished in may generally be obtamed the followmg ways:

(I) The reaction of an isocyanate prepolymer (i.e. a lg g thlsd mvemlon ig g by higher molecular weight compound containing at least two P mg 8 ape Pro nets a 0d or t 6 pro terminal isocyanate groups) with water or a polyamine. Fhereof from aqueous dlsperslon? of of (II) The reaction of an amino prepolymer (i.e. a higher olefimcally unsaturated compounds which dispersions are molecular weight compound containing at least two termi Coagulated y Produclng a P y -P M nal amino groups which may be primary or secondary) tion product therein.

with a dior polyisocyanate. The term Shaped molded Product as used hefeln 15 (III) The reaction of an isocyanate prepolymer with an intended to cover any shaped article including materials amino prepolymer.

These reactions as well as the starting materials employed therein are known and have been described, for example, in Houben-Weyl Makromolekulare Stotfe, part 2, Stuttgart 1963, page 83 and pages 169 and 171. Such reactions may be carried out as follows:

METHOD I The isocyanate prepolymers referred to as A prepolymers in the examples are prepared in known manner by reacting an excess of a polyisocyanate with a higher molecular weight compound containing at least two active hydrogen atoms as determined by the Zerewitinotf method. Some suitable higher molecular weight active hydrogen containing compounds which may be thus employed include those listed in US. Pat. No. 3,201,372 and mixtures thereof in addition to any suitable polyesters or polyester amides prepared from hydroxycarboxylic acids, dicarboxylic acids, polyols, polyamines, hydrazines, amino alcohols or aminocarboxylic acids using known methods. Some suitable acids which may be used include hydroxycaproic acid, malonic acid, succinic acid, adipic acid, methyladipic acid, sebacic acid, thiodipropionic acid, maleic acid, phthalic acid and terephthalic acid. Some suitable polyols which may be used include ethylene glycol, di-, tri and poly-ethylene glycols, polypropylene glycols, butane-1,3- diol and -l,4-diol, hexane-1,6-diol, acetals produced by the reaction of glycols with formaldehyde, glycerol, pentaerythritol, trimethylol propane and hexane-1,2,6- triol. Amines such as, for examples, ethylene diamine, tetramethylene 1,4-diamine, hexamethylene-l,6-diamine, piperazi-ne, 1,3- and 1,4-phenylene diamine, ethanolamine, propanolamine and N-methyldiethanolam-ine may also be used.

Any suitable polyethers including those obtained, for example, by the addition of alkylene oxides such as ethylene oxide or propylene oxide to water, hydrogen sulphide, ammonia or polyols such as ethylene glycol, propane-1,3- and -l,2-diol, trimethylol propane, glycerol and di(hydroxyalkyl)-alkylamines are also suitable. If desired in the preparation of such polyethers several different alkylene oxides may enter into the reaction simultaneously or successively. Polythioethers prepared, for example, by the condensation of thiodiglycol with itself or by reaction with alkylene oxides are also suitable. Polyacetals such as those formed, for example, from hexane- 1,6-diol with formaldehyde may also be used as a starting material for the preparation of the A prepolymers, as may polysiloxanes prepared, for example, by reacting dialkylsilicon dihalides with water.

The molecular weight of the above mentioned higher molecular weight compounds containing active hydrogen atoms preferably lies between about 500 and about 10,000.

The prepolymer is obtained by reacting an excess of any suitable organic polyisocyanate with the active hydrogen containing compound. Some such suitable polyisocyanates include any of those listed herein as well as those suggested in US. Pat. No. 3,201,372, Canadian Pat. No. 698,636 and mixtures thereof.

The NCO prepolymers thus obtained (prepolymers A) are either reacted with water which, in any case, is present in the polymer latices, or with any suitable compounds containing at least two basic amino groups. Some such suitable amino compounds include low molecular weight polyamines such as, for example, ethylene diamine, diethylene triamine, polyethylene polyamines, propylene-1, 3-diamine, dipropylene triamine, polypropylene polyamines, tetramethylene-1,4-diamine, pentamethylene-1,5- diamine, hexamethylene-l,6-diamine, dodecamethylene- 1,12-diamine and homologous compounds, N-monoalkylated and N,N-dialkylated diamines such as N-methy1 1,3 diaminopropane, N,N' dimethylethylene diamine, cycloaliphatic diamines such as 1,3- and 1,4-hexahydrophenylene diamine, tetrahydronaphthylene diamines, 4,4- diaminodicyclohexylmethane, perhydrobenzidine, 1,5-diamino Decalin, heterocyclic diamines such as piperazine,

2,5-dimethy1piperazine, imidazolidine, aromatic diamines such as 1,3- and 1,4-phenylene diamine, l,3-, l,4- and 1,5- naphthylene diamine, benzidine, 4,4-diamino-diphenylmethane, 4,4,4"-triamino-triphenylmethane, tolylene diamines such as 2,4- and 2,6-tolylene diamine as well as isomeric mixtures thereof, perhydrogenated 2,4- and 2,6- tolylene diamine and isomeric mixtures thereof, deriva tives of these compounds which are alkylated on the nucleus or monoalkylated on the nitrogen atom, araliphatic diamines such as 4-aminobenzylamine, amino phenyl ethylamincs, N-methyl-p-aminobenzylamine and its homologues, 1,4-xylylene diamine, hydrazine, hydrazines which are monoalkylated on one or both N- atorns, dicarboxylic acid dihydrazides such as carbodihydrazide, adipic acid dihydrazide, amino carboxylic acid hydrazides such as aminoacetic acid hydrazide, e-aminocaproic acid hydrazide, aminobenzoic acid hydrazide, aminosulphohydrazides such as aminobenzylsulphohydrazide and bis-semicarbazides; bishydrazide compounds of the formula in which R represents an alkylene radical having 2 to 12 carbon atoms, e.g.

may also be used. The bishydrazide compounds may be prepared, for example, as described in Canadian patent specification No. 805,703. Diamines or bishydrazide compounds are preferably used in the process according to the invention.

When carrying out the reaction, the NCO groups and NH groups respectively OH groups (from water) are preferably employed in at least equivalent quantities. If the amounts are substantially below equivalent or stoichiometric quantities, products of inferior quality are obtained.

METHOD II The amino prepolymers referred to as B prepolymers in the examples can be prepared by numerous methods which are well known. Such substances are easily obtained by the addition of an excess of a low molecular weight polyamine or hydrazine to a compound containing NCO groups. For example, an NCO prepolymer or a low molecular weight monomeric polyisocyanate, preferably in solution, is run with vigorous stirring into a solution of one of the low molecular weight polyamines enumerated hereinbefore in a reaction vessel which may be cooled. The NCO prepolymer is prepared as described in the preparation of the A prepolymers and the same polyisocyanates and active hydrogen containing compounds may be employed. The NH/NCO ratio should be greater than 1 and preferably between about 1.5 and about 5. If very reactive polyamines are used, the NH/NCO ratio is advantageously greater than 5 an any excess unreacted polyamine can be distilled oif after the reaction is completed. In order to reduce the amount of excess polyamine which may be present, it may be converted, for example, into its carbonate or carbamic acid derivatives.

Some other compounds which may be used as B type prepolymers in the instant process include the reaction products of an A prepolymer with a sulphamic acid as described in Deutsche Auslegeschrift No. 1,555,907. Another possible method which may be used for synthesizing B type prepolymers is given in French Pat. No. 1,415,- 317 which describes the conversion of A type prepolymers into N-formyl derivatives with formic acid followed by partial saponification to yield the amino derivative which is a B type prepolymer. Such prepolymers can also be obtained as described in Belgian Pat. No. 675,425 by adding secondary or tertiary carbinols to A type prepolymers and decomposing the resulting carbamic acid ester into the corresponding amine via an acid catalyzed reaction.

Very highly reactive molecular weight B type prepolymers can be prepared as described, for example in Deutsche Auslegeschrift No. 1,215,373, by reacting higher molecular weight hydroxyl compounds with ammonia or amines under pressure in the presence of a catalyst and at a suitable temperature. Higher molecular weight h y droxyl components may also be reacted with acrylonitrile and then hydrogenated catalytically as described in US. Pat. No. 3,044,989. Acid catalyzed reaction products of aminoethyl 5,6 dihydro-(4H) pyran derivatives and higher molecular weight hydroxyl components as described in Dutch Auslegeschrift No. 6,601,435 may also be used. Lastly, B type prepolymers which have a satisfactory reactivity and a good solubility in OIgEIHC SOI- vents can be prepared according to the process outlined in US. Pat. No. 2,888,439 by the addition of nitroaryl isocyanates or, according to French Pat. No. 1,4:/4,551, by the addition of isocyanatoazobenzene derivatives to higher molecular weight hydroxyl components followed by reduction. According to the process described in Canadian patent specification 805,703 higher molecular weight compounds which contain terminal OH groups can be made to undergo an ester interchange reaction with diphenylcarbonate accompanied by the evolution of phenol; carboxylic acid phenol esters react with hydrazine to form hydrazodicarbonic acid esters, phenol again being sp lit 01f. These compounds are also suitable for use in this invention because they contain reactive terminal NH groups. All the B type prepolymers prepared in this manner are suitable for use in the practice of this invention and they can be reacted with the usual dior polyisocyanates.

Some suitable organic polyisocyanates which may be used in the practice of this invention include 1,4-tetraniethyleneand 1,6 hexamethylenediisocyanates, 1,4- cyclohexanediisocyanate, mand p-phenylenediisocyanates, 2,4- and 2,6-tolylene diisocyanates and isomeric mixtures thereof as well as the corresponding hydrogenation products, p-xylene diisocyanate, 4,4-diphenylether diisocyanate, 4,4 diphenylsulphone-diisocyanate, 4,4- diphenylmethane diisocyanate, 2,2 di(p isocyanatophenyl)-propane, 3,3 dimethyldiphenylmethanef,4'-diisocyanate, 3,3 dichlorodiphenylmethane-4,4'-di isocyanate, 1,5 naphthylene diisocyanate, 4,4',4" triphenyl methane triisocyanate, tri-p-isocyanato-phenyl-thiophosphate, the material produced by the reaction of 1 rnol of trimethylol propane with 3 mols of tolylene-2,4-d11socyanate, the reaction product derived from 3 mols of 1,6- hexamethylene diisocyanate and 1 mol of water, which reaction product has the formula and any of those suggested elsewhere herein. The use of diisocyanates is preferred. In this reaction also the NCO and NH groups respectively OH groups should be used in at least equivalent amounts.

METHOD III The starting materials for this reaction have already been set forth in the discussion given with respect to Methods I and II. All of the prepolymers and low molecular weight compounds mentioned herein may be used either alone or in solution in a suitable solvent. Again, the NCO and HN groups respectively OH groups should be used in at least equivalent amounts.

PRODUCTION OF THE MOLDED PRODUCT The process is usually carried out by emulsifying the polymer latex described hereinbefore with one of the starting components for the formation of the polyurethane polyurea, and then emulsifying the second component which is mixed therewith and immediately shaping the resulting mixture. If water is used as a cross-linking agent, it may be necessary to add a cross-linking catalyst. Other liquids which are nonsolvents for the polymers, such as petroleum hydrocarbons, alcohol or ether may also be added to the emulsion and sometimes it is advisable to add more water to the dispersion. After the shaping and solidification of the polymer mixture, the excess solvent, nonsolvent and/or water are evaporated off in the usual manner.

The proportion of polyurethane polyurea to polymer in the aqueous polymer dispersion may lie between about 2% and about 98% of polyurethane polyurea based on the total solids present. The total solids present preferably consist of from about 10% to about of polyurethane polyurea and in one embodiment, from about 30% to about 60%. Coagulation of the polymer latex can be carried out at temperatures of between about 0 and about 98 C., preferably between 25 and 60 C.

Emulsiifiers, fillers, vulcanization or cross-linking agents, stabilizers, dyes, pigments and higher molecular weight siloxanes which improve the hydrophobic character of the products as well as silicone compounds may be included in the dispersions. It is also possible to produce porous foils by adding compounds which are nonsolvents both for the polymer of the olefinically unsaturated compounds and for the polyurethane elastomer to be produced. In such cases the breadth of variation of the starting components with respect to the microporosity of the product is not as great.

To produce microporous elastic foils, the molded product must have Shore A values of more than about 40 and preferably more than about 65, tensile strengths of more than about 70 kg. wt./cm. and softening points above about 100 C. If the Shore A hardness is too low, the polymer tends to lose its microporosity when subjected to pressure. The determination of suitable starting components can easily be made by preparing a sample of the final product in non-microporous form from said starting materials and determining the tensile strength, Shore A hardness and softening point of this sample. They have to meet the above requirements.

The microporosity of the product is produced by the nonsolvent used so that it is necessary to use more than 15% andpreferably more than about 40% by weight of nonsolvent based on the sum of the weights of the olefin polymer, starting components for the polyurethane elastomer and solvent.

The final properties of the molded product depend on the properties of the olefin polymer and the polyurethane polyurea elastomer used. Thus, for example, soft elastic foils can be produced from an olefin polymer dispersion which would otherwise yield hard, nonelastic foils by incorporating a polyurethane having suitable properties therein. If the polymer by itself yields only sticky soft molded products, an elastic molded product can still be produced by incorporating a hard polyurethane.

A particularly preferred embodiment comprises plasticizing dispersions of hard olefin polymers which have little tendency to form films with polyurethanes in accordance with this invention.

A commercial polyvinyl chloride dispersion, for example, does not yield a film on drying but only loosely coherent polymer particles. If polyaddition is carried out according to the process of this invention; that is, the polyaddition of a prepolymer which contains NH groups and an NCO prepolymer in the polyvinyl chloride dispersion, highly elastic products are obtained after evaporation of the water and solvent which contains a polyurea acting as a nonvolatile plasticizer which is resistant to migration The products of this invention are particularly useful for lining vessels, as packaging foils, for coating or covering metals, woven fabrics, non-Wovens, leather and wood and so on.

The invention is further illustrated but is not intended to be limited by the following examples in which all parts and percentages are by weight unless otherwise specified.

7 PREPARATION OF PREPOLYMERS CONTAINING ISOCYANATE GROUPS.A TYPE PREPOLYMERS About 2,000 parts of a linear polypropylene glycol ether having a molecular weight of about 2,000 are mixed NCO-CONTAINING PREPOLYMERS AS TO A22 ARE PREPARED AS DESCRIBED IN A1 TO A3 USING THE COMPONENTS AS INDICATED IN THE FOLLOWING TABLE Higher molecular weight compound containing at least two active No. hydrogen atoms A8 Linear polypropylene glycol ether (molecular weight12000, Oll 4.4-dipheuyl.mothane diisoeyanatc 1:1.5

Pol yisocyanate 1. 64 Yellow resin.

number 56 A!) do .do 1:3 6. 2 Do. All Mixture of a polysiloxane having the formula HO-CII2 (SI(CI{2)2' .do 1:2 3. 08 Do.

)i2 a)2-CH;*OH and alinear polypropylene glycol ether (molecular weight 2000, OH number 56). in a molar ratio of 1:3. A14". Copolyether of 80% propylene oxide and ethylene oxide (molee- LG-hexamethylcne diisoeyauate. 1 2 2. 5 1,875 cp./ C.

ular weight 4150, OH number 27). A19. Polyester of adipic acid and a mixture of 65 parts oll1exane-1.6-diol .do 1:2 4.1 Consistency of and parts of 2.2-dimethylpropane-1.3-di0l (molecular weight 1,700, OH number 66).

A20. Polyester of adipic acid and a mixture of hexane-LS-diol and 2.2 dimethyl-propane-l.3-diol in a molar ratio of 11:6 (molecular weight 1,870, OH number 52).

A22 Polyester of adipic acid and diethylene glycol (molecular weight Isomerie mixture of 2.4-and 2.6-

tolylene diisocyanate (80: 20)

600, OH number 187).

with about 336 parts of 1,6-hexamethylene diisocyanate and heated to about 110 C until the free isocyanate group content drops to about 3.5%, which requires about 8 to 9 hours A slightly yellowish oil having a viscosity of about 2125 cp./25 C. is obtained.

About 250 parts of 4,4'-dipheny1methane diisocyanate are added to about 1,000 parts of a linear polypropylene glycol ether having a molecular weight of about 2,000 and heated to about 80 C. for about 6 hours. A viscous yellow oil which contains about 3.3% of free isocyanate groups is obtained.

About 1,700 parts of a polyester prepared from adipic acid and a mixture of hexane-1,6-diol and 2,2-dimethylpropane-1,3-diol in the ratio of :35 and having a molecular weight of about 1,700 and OH number of 66 are heated to about C. and about 348 parts of tolylene-2,4 diisocyanate are added. After about minutes at about 80 C., the NCO content drops to about 4.1%. A pale yellow product which has the consistency of an ointment is obtained.

About 500 parts of a polyester prepared from phthalic acid, adipic acid and ethylene glycol and having an average molecular weight of about 1,666 (OH number 67.4) are dehydrated at about C./12 mm. Hg and about 113 parts of 4,4'-diphenylmethane diisocyanate are added. After about 15 minutes at about 130 C. the NCO content of the yellow resin is about 1.8%.

About 990 parts of a copolyether prepared by the alternate polymerization of ethylene oxide and propylene oxide in a ratio of 1:1 using butane-1,4-diol as starter PREP OLYMERS tt diphenylmethane diisoeyanate. 1:1. 5

ointment.

1 2 10. 6 Highly vis- PREPARATION OF PREPOLYMERS WHICH CON- TAIN AMINO END GROUPS.B TYPE PRE- POLYMERS About 7 parts (0.1285 mol) of hydrazine hydrate and about 315 parts of tetrahydrofuran are introduced into a 3 liter glass beaker and a solution of about 300 parts of the NCO-prepolymer A4 (0.1285 mol NCO) in about 450 parts of toluene and about parts of tetrahydrofuran are run into this mixture with vigorous stirring and cooling with ice in the course of about 15 minutes. A thick liquid 25% solution of a prepolymer containing semicarbazide end groups is obtained.

A solution of about 457 parts (0.385 mol NCO) of prepolymer A5 in about 300 parts of water are added in the course of about 10 minutes to a solution of about 20 parts of hydrazine hydrate (0.385 mol) in about 165 parts of water and contained in a 3 liter glass beaker, with vigorous stirring and cooling with ice. A viscous 50% aqueous solution of a prepolymer containing semicarbazide end groups is obtained.

About 5 parts (0.103 mol) of hydrazine hydrate are dissolved in about 100 parts of water in a 2 liter glass beaker and about 40 parts of prepolymer B2 are added.

In a second glass beaker, about 100 parts (0.0856 mol NCO) of prepolymer A1 and about 20 parts (0.0174 rnol NCO) of prepolymer A5 are emulsified with vigorous stirring in about 167 parts of water in a second glass beaker, and the emulsion is poured into a solution prepared as described above in the course of about 5 minutes with vigorous stirring. An about 33.3% aqueous emulsion of a prepolymer containing semicarbazide end groups is obtained.

TO B22 WHICH CONTAIN AMINO GROUPS ARE PREPARED AS SING THE COMPONENTS AS INDICATED IN THE FOLLOWING I fl I j IN B1 To B3 Prepolymor NCO N Solution con- A I centration ctive NlI Number A number Diamme ratio Solvent (percent) (nmiol/g.

I-Iydrazine 1:2 Benzene 50 O 637 d 1:2 Toluene 33.3 0:141 4-annno phenylethylamme 1 :2 Tetrahydrofurau 30 O. 363 (1 1:2 Benzene 40 0,155 1:2 Tetrahydroturan 40 0. 1 :2 Dnsopropyl ether 33. 3 0.195 t:2 Ethyl a-:etate 33.3 0.103 1:2 Toluene 33. 3 0. 267

About 1950 parts (1.0 mol) of polypropylene glycol- (1,2)-ether are added to about 329 parts (2 mol) of distilled p-nitrophenylisocyanate in about 1.5 liters of tetrahydrofuran and the solution stirred for about 2 hours at reflux temperature. After the addition of Raney nickel the product is hydrogenated at about 100 C. using about 50 excess atmospheres of hydrogen, filtered and the solvent is evaporated under reduced pressure. The diamine yield is greater than 99% of the theoretical; NH number 50.5.

EXAMPLE 1 About 10 parts of a 60% dispersion of an emulsion of polyvinyl chloride (K value 70) and about 180 ml. of water are dispersed in a mixture of about 50 ml. of a 0.2 molar solution in benzene of NCO prepolymer A14 (10) mmol NCO) and 25 ml. of prepolymer A19 5 mmol NCO) using high speed stirrer operating at about 4000 to about 6000 revs/min. About 7.5 ml. of a 1 molar aqueous solution of hexamethylene diammonium carbonate (15 mmol NH are then added and the reaction mixture is stirred for about seconds before being poured onto a glass plate having an area of about 100 cm. and heated at about 80 C. to complete the polyaddition. A microporous film having the following properties is obtained: Permeability to water vapor: (IUP published e.g. in

Das Leder 1961, 86-88): 1.5 mg./h. cm. Flexometer: 200,000 bends (1UP published e.g. in

Das Leder 1964, 87-88) Tensile strength: 26.7 kg. wt./cm. (TUP 6; published e.g.

in Das Leder 1959, 14-18) Elongation at break: 130% (1UP 6) Tear propagation resistance: 14 kg. wt./ cm. (1UP 8;

published in Des Leder 1961, 39-40) IUP: International Union for Physical Testing EXAMPLE 2 About parts of a emulsion of a copolymer of acrylonitrile and butadiene are dispersed with about 4% of methacrylic acid and about 250 ml. of water in about 64 parts (10 mmol NH of NH prepolymer B18 and 100 parts of ethyl acetate. After the addition of about 5 ml. (10 mmol NCO) of a 2 N solution in benzene of 4,4-diphenylmethane diisocyanate, the reaction mixture is stirred for about 10 seconds and then poured onto a steel support and dried at about 75 C. A microporous film having the following properties is obtained:

Permeability of water vapor-1.6 mg./h. cm. Flexometer 200,000 bends Tensile strength19 kg. wt./cm.

Elongation at break5 80% Tear propagation resistance9 kg. wt./cm.

Part of the above dispersion is poured onto a siliconebacked paper from which it is then removed and dried at about 100 C./100 mm. Hg. A microporous film is obtained which has properties similar to those listed above.

Tear propa- Permegation ability Stir- Drying Tensile Elongaresistto water ring temper- Flexstrength tion at ance vapor Shore time ature ometer (kg. wt./ break, (kg.wt./ (mg./ hard- (g.) (see) C.) (bends) cm!) percent em.) hem?) nessA Remarks 10 75 2.9

TABLE I.THE FOLLOWING TESTS ARE CARRIED OUT AS DESCRIBED IN EXAMPLE 1 Or (ml) Or (ml.) 0.2 molar 1 molar solution Polymer Quanaqueous (based on Mmol dispersion, tity Water so1uti0n= (g.) NCO) Solvent NCO Table 0 (g.) (ml.) Polyamine (g.) mmol NH; Solvent A3 50 Benzene. 10 C8 10 110 p-Aminophenyl 10 ethylamine.

N C 0 me polymer 70 Catalyst: N- methyl-N'- (N-dimethylamlnoethyl) piperazlne; (cross-linking with water) 30 100 diamine.

70 Hydrazlne hydrate in water).

10 50 4,4-dihydrazlno-stilbene dlsulphonic acid-2,2.

m om

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What is claimed is:

1. A process for preparing sheet structures which comprises emulsifying an aqueous emulsion of a thermoplastic or elastomeric polymer of an unsaturated monomer which emulsion has a solids content of to 70 percent by weight into a reaction product of (a) a compound containing at least two hydrogen atoms reactive with NCO groups and having a molecular Weight of between 500 and 10,000 and a molar excess of a polyisocyanate or (b) a molar excess of an organic polyamine with (a); adding a crosslinking agent for (a) or (b) to the resulting dispersion in the presence of a nonsolvent for the polymer from (a) and (b) which crosslinking agent is a polyamine in case (a) and an organic polyisocyanate in case (b);

immediately shaping the dispersion to form a sheet structure and evaporating volatile liquid constituents from the sheet with the proviso that more than by weight of non-solvent based on the sum of the weights of the polymer of the unsaturated monomer, (a), (b) and the other liquid constituents is present.

2. The process of claim 1 wherein the thermoplastic or elastomeric polymer is natural rubber, polybutadiene, polyisoprene, polychloroprene, styrene butadiene copolymer, butadiene acrylonitrile copolymer, polyvinyl chloride, polyvinylidene chloride, polystyrene, ethylene vinyl acetate copolymer, polyacrylonitrile, styrene acrylonitrile copolyrner, butadiene acrylonitrile methacrylic acid copolymer or butadiene styrene acrylonitrile and methacrylic acid copolymer.

3. The process of claim 1 wherein the thermoplastic polymer is polyvinyl chloride.

4. The process of claim 1 wherein the solids content is from 30% to References Cited UNITED STATES PATENTS 3,326,848 6/1967 Clemens et al. 260-292 TN 3,438,940 4/1969 Keberle et al. 260-296 iNR 3,472,807 10/1969 Isaacs u 260-296 NR 3,491,050 1/1970 Keberle et al. 260-296 NR 3,536,638 10/1970 Dosmann 2602.5 AY 3,100,721 8/1963 Holden 264-41 UX 3,190,765 6/1965 Yuan 264-41 UX 3,238,055 3/1966 Brightwell 264-41 UX 3,296,016 1/ 1967 Murphy 264-41 UX 3,348,963 10/1967 Fukushima et a1. 26441 UX 3,369,925 2/1968 Matsushita et a1. 264 -41 UX 3,388,100 6/1968 Thoma et a1 264-41 UX 3,403,046 9/1968 Schwacke et a1. 264-41 UX FOREIGN PATENTS 639,553 4/1962 Canada 264-41 PHILIP E. ANDERSON, Primary Examiner US. Cl. X.R.

117-161 KP; 260-25 AY, 29.2 TN, 29.6 NR, 77.5 AX, 77.5 CH, 859; 26453, 331, Dig. 62, Dig. 77 

